1. Field of the Invention
The present invention relates to a liquid ejection head for ejecting liquid such as ink, and a recording method and a suction method using the liquid ejection head.
2. Description of the Related Art
As a liquid ejection head (hereinafter simply referred to as recording head) used in a liquid ejection apparatus, one in which an orifice plate is bonded to a substrate having a supply opening formed therein is manufactured in high volume. An exemplary structure of such a recording head is described with reference to FIGS. 19A and 19B.
FIG. 19A is a plan view of a related recording head seen from a direction of ink ejection, and FIG. 19B is a sectional view of the recording head taken along the line 19B-19B of FIG. 19A. As illustrated in FIGS. 19A and 19B, a recording head 1 includes a substrate 2, an orifice plate 3, and a common liquid chamber 4 formed by bonding the substrate 2 and the orifice plate 3 together.
A liquid receiving portion 5 for receiving ink from an ink tank (not shown) as an ink supply source is provided on a surface of the substrate 2 on a side opposite to the side bonded to the orifice plate 3. The liquid receiving portion 5 has a supply opening 6 formed therein which communicates to the common liquid chamber 4. Ink supplied to the liquid receiving portion 5 is supplied through the supply opening 6 to the common liquid chamber 4.
Multiple ejection orifices 7 for ejecting ink are formed in the orifice plate 3 so as to sandwich the common liquid chamber 4 therebetween. Pressure chambers 8 are formed between the substrate 2 and the orifice plate 3 in regions corresponding to the respective ejection orifices 7. An energy generating element 9 such as a heater for supplying ejection energy to ink in each pressure chamber 8 is provided in each pressure chamber 8. Each pressure chamber 8 communicates through a flow path 10 to the common liquid chamber 4, and ink in the common liquid chamber 4 is supplied through the flow path 10 to each pressure chamber 8.
Further, the recording head 1 includes, in the ink path from the common liquid chamber 4 to each pressure chamber 8, a filter 11 for trapping foreign matter in ink. Ink in the ink tank may contain foreign matter. If foreign matter together with ink flows into the pressure chamber 8 and attaches to the ejection orifice 7, the ejection orifice 7 is clogged and ink is prevented from being ejected. The filter 11 may prevent foreign matter from flowing into the pressure chamber 8, and may inhibit clogging of the ejection orifice 7.
Next, ink flow from the supply opening 6 to the pressure chamber 8 is described with reference to FIGS. 20A and 20B. FIGS. 20A and 20B are sectional views of a recording head having multiple common liquid chambers 4 and supply openings 6 taken along a line passing through the common liquid chambers 4, the supply openings 6, and the ejection orifices 7. Note that, a suction cap 12 for sucking ink from the ejection orifices 7 is mounted onto the recording head illustrated in FIGS. 20A and 20B.
The supply opening 6 is connected to an ink tank (not shown) as an ink supply source, and ink is supplied from the ink tank through the supply opening 6, the common liquid chamber 4, and the flow path 10 to the pressure chamber 8.
Ink in the pressure chamber 8 receives ejection energy from the energy generating element 9 and flows out from the ejection orifice 7. As illustrated in FIG. 20A, ink in the pressure chamber 8 flows out from the ejection orifice 7 also with the help of the suction cap 12. When ink in the pressure chamber 8 decreases in quantity, ink is supplied again from the ink tank through the supply opening 6 and the like to the pressure chamber 8.
As illustrated in FIG. 20B, ink supplied to each pressure chamber 8 is supplied through only one flow path 10. Therefore, in the recording head illustrated in FIGS. 19A and 19B or FIGS. 20A and 20B, refill characteristics (characteristics represented as time from a point at which ink flows out of the ejection orifice 7 to a point at which the pressure chamber 8 is filled with ink) are not always sufficient. Accordingly, a recording head with improved refill characteristics has been proposed.
In a recording head disclosed in Japanese Patent Application Laid-Open No. 2008-254304, multiple common liquid chambers communicating to one supply opening are formed so as to sandwich their pressure chamber. A flow path is formed from each of two common liquid chambers sandwiching one pressure chamber to the pressure chamber. Ink is supplied from two common liquid chambers through the flow paths to one pressure chamber, and thus, the ink refill characteristics are improved.
In the recording head described in Japanese Patent Application Laid-Open No. 2008-254304, ink is supplied through one supply opening to a pressure chamber, and thus, there is a ceiling on improvement in the ink refill characteristics. In particular, when printing is carried out at high speed in a higher duty cycle, more ink is required to be supplied to the pressure chamber, and thus, refilling the pressure chamber with ink sometimes becomes too late.
Japanese Patent Application Laid-Open No. 2009-039914 discloses a recording head having higher refill characteristics than those of the recording head described in Japanese Patent Application Laid-Open No. 2008-254304.
Specifically, in the recording head described in Japanese Patent Application Laid-Open No. 2009-039914, multiple supply openings are formed correspondingly to common liquid chambers formed so as to sandwich pressure chambers. A flow path is formed from each of two common liquid chambers sandwiching one pressure chamber to the pressure chamber, and thus, ink is supplied through two supply openings, two common liquid chambers, and two flow paths to one pressure chamber. Therefore, the recording head described in Japanese Patent Application Laid-Open No. 2009-039914 has improved ink refill characteristics compared with the recording head described in Japanese Patent Application Laid-Open No. 2008-254304.
However, in the recording head disclosed in Japanese Patent Application Laid-Open No. 2009-039914, multiple liquid receiving portions are formed correspondingly to the supply openings, and an ink flow path is formed from an ink tank to each liquid receiving portion. Therefore, foreign matter contained in ink in the ink tank may pass through all the supply openings. In other words, foreign matter, together with ink, may flow in all the common liquid chambers. Therefore, it is necessary to provide a filter in every ink path from the common liquid chambers to the pressure chambers.
As illustrated in FIGS. 19A and 19B, when the filter 11 is provided in the recording head 1, space for providing the filter 11 is required to be secured on the substrate 2. It follows that, as the number of the filters 11 increases, the substrate 2 is required to be larger.
As the substrate becomes larger, the number of substrates which may be taken from one wafer in the manufacturing of the recording head becomes smaller, which results in an increase in manufacturing cost of the recording head. Further, as the substrate becomes larger, the orifice plate also becomes larger accordingly and the recording head becomes larger. As a result, the liquid ejection apparatus as a whole becomes larger. When a suction cap is provided for the liquid ejection apparatus, as the recording head becomes larger, the suction cap also becomes larger.
In particular, when the colors of ink ejected from the recording head increase, the number of the ejection orifices and the number of the pressure chambers increase so that the substrate becomes still larger, and thus, the manufacturing cost of the recording head conspicuously increases and the liquid ejection apparatus conspicuously becomes larger.